U.S. patent application number 12/912243 was filed with the patent office on 2011-06-02 for laser induced thermal imaging method, method of patterning organic layer using the same and method of fabricating organic light emitting diode display device using the same.
This patent application is currently assigned to Samsung Mobile Display Co., Ltd.. Invention is credited to Hyung-Sik Kim, Hyun-Chul LEE, Won-Kyu Lim, Jin-Han Park, Cheol-Lae Roh.
Application Number | 20110129779 12/912243 |
Document ID | / |
Family ID | 44050305 |
Filed Date | 2011-06-02 |
United States Patent
Application |
20110129779 |
Kind Code |
A1 |
LEE; Hyun-Chul ; et
al. |
June 2, 2011 |
LASER INDUCED THERMAL IMAGING METHOD, METHOD OF PATTERNING ORGANIC
LAYER USING THE SAME AND METHOD OF FABRICATING ORGANIC LIGHT
EMITTING DIODE DISPLAY DEVICE USING THE SAME
Abstract
A laser induced thermal imaging (LITI) method, a method of
patterning an organic layer using the same and a method of
manufacturing an organic light emitting diode (OLED) display device
using the same. The LITI method includes preparing a substrate
including a transfer layer, preparing a donor substrate including a
base film and a light-to-heat conversion layer disposed on the base
film, aligning the substrate with the donor substrate, and
irradiating laser to the base layer of the donor substrate. Here,
the laser is irradiated to the base layer in a region excluding a
region corresponding to a pattern to be formed on the substrate.
Thus, according to the method, regardless of the size of the
pattern to be formed and the size of the laser beam, stitching mura
can be prevented.
Inventors: |
LEE; Hyun-Chul;
(Yongin-City, KR) ; Park; Jin-Han; (Yongin-City,
KR) ; Kim; Hyung-Sik; (Yongin-City, KR) ; Lim;
Won-Kyu; (Yongin-City, KR) ; Roh; Cheol-Lae;
(Yongin-City, KR) |
Assignee: |
Samsung Mobile Display Co.,
Ltd.
Yongin-City
KR
|
Family ID: |
44050305 |
Appl. No.: |
12/912243 |
Filed: |
October 26, 2010 |
Current U.S.
Class: |
430/312 ;
430/319; 430/322; 430/325 |
Current CPC
Class: |
H01L 51/56 20130101;
H01L 27/3211 20130101; H01L 51/0013 20130101; B41M 5/38214
20130101; C23C 14/048 20130101 |
Class at
Publication: |
430/312 ;
430/322; 430/325; 430/319 |
International
Class: |
G03F 7/20 20060101
G03F007/20 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 30, 2009 |
KR |
10-2009-0116424 |
Claims
1. A laser induced thermal imaging method, comprising: preparing a
substrate including a transfer layer; preparing a donor substrate
including a base layer and a light-to-heat conversion layer
disposed on the base layer; aligning the substrate with the donor
substrate; and irradiating laser to the base layer of the donor
substrate, wherein the laser is irradiated to the base layer in a
region excluding a region corresponding to a pattern to be formed
on the substrate.
2. The method according to claim 1, wherein the laser has a
transfer energy intensity of 5 to 40 kW/cm.sup.2.
3. The method according to claim 1, further comprising, after the
substrate is aligned with the donor substrate, laminating the donor
substrate and the substrate.
4. The method according to claim 1, further comprising, after the
laser is irradiated to the base layer of the donor substrate,
delaminating the donor substrate from the substrate.
5. The method according to claim 4, wherein the transfer layer, in
the region excluding the region corresponding to the pattern to be
formed on the substrate, is adhered to the donor substrate and
separated from the substrate through the delamination.
6. A method of patterning an organic layer, comprising: preparing a
substrate including an organic layer; preparing a donor substrate
including a base layer and a light-to-heat conversion layer
disposed on the base layer; aligning the substrate with the donor
substrate; and irradiating laser to the base layer of the donor
substrate, wherein the laser is irradiated to the base layer in a
region excluding a region corresponding to a pattern to be formed
on the substrate.
7. The method according to claim 6, wherein the laser has a
transfer energy intensity of 5 to 40 kW/cm.sup.2.
8. The method according to claim 6, further comprising, after the
substrate is aligned with the donor substrate, laminating the donor
substrate and the substrate.
9. The method according to claim 6, further comprising, after the
laser is irradiated to the base layer of the donor substrate,
delaminating the donor substrate from the substrate.
10. The method according to claim 9, wherein the organic layer, in
the region excluding the region corresponding to the pattern to be
formed on the substrate, is adhered to the donor substrate and
separated from the substrate through to the delamination.
11. The method according to claim 6, wherein the organic layer is
formed of a single layer selected from the group consisting of an
emitting layer, a hole injection layer, a hole transport layer, an
electron injection layer, and an electron transport layer, or a
multiple layer including at least two thereof.
12. A method of manufacturing an organic light emitting diode
(OLED) display device, comprising: forming a first electrode layer
on a substrate; forming an insulating layer on the first electrode
layer to define a first pixel region, a second pixel region, and a
third pixel region; applying a first light-emitting material to the
entire surface of the substrate including the first, second and
third pixel regions; preparing a donor substrate including a base
layer and a light-to-heat conversion layer disposed on the base
layer; aligning the substrate with the donor substrate; and
irradiating a laser to the base layer of the donor substrate,
wherein the laser is irradiated to the base layer in a region
excluding a region corresponding to the first pixel region.
13. The method according to claim 12, further comprising, after the
laser is irradiated to the base layer in the region excluding the
region corresponding to the first pixel region, delaminating the
donor substrate from the substrate, wherein, through the
delamination, the first light-emitting material in the region
excluding the region corresponding to the first pixel region is
adhered to the donor substrate and thus separated, and the first
light-emitting material in the region corresponding to the first
pixel region remains on the substrate, thereby forming a first
light-emitting material pattern.
14. The method according to claim 13, further comprising: applying
a second light-emitting material to the entire surface of the
substrate including the first light-emitting material pattern;
preparing a donor substrate including a base layer and a
light-to-heat conversion layer disposed on the base layer; aligning
the substrate with the donor substrate; and irradiating the laser
to the base layer of the donor substrate, wherein the laser is
irradiated to the base layer in a region excluding a region
corresponding to the second pixel region.
15. The method according to claim 14, further comprising, after the
laser is irradiated to the base layer in the region excluding the
region corresponding to the second pixel region, delaminating the
donor substrate from the substrate, wherein, through the
delamination, the second light-emitting material in the region
excluding the region corresponding to the second pixel region is
adhered to the donor substrate and thus separated, and the second
light-emitting material in the region corresponding to the second
pixel region remains on the substrate, thereby forming a second
light-emitting material pattern.
16. The method according to claim 15, further comprising: applying
a third light-emitting material to the entire surface of the
substrate including the first and second light-emitting material
patterns; preparing a donor substrate including a base layer and a
light-to-heat conversion layer disposed on the base layer; aligning
the substrate with the donor substrate; and irradiating the laser
to the base layer of the donor substrate, wherein the laser is
irradiated to the base layer in a region excluding a region
corresponding to the third pixel region.
17. The method according to claim 16, further comprising, after the
laser is irradiated to the base layer in the region excluding the
region corresponding to the third pixel region, delaminating the
donor substrate from the substrate, wherein, through the
delamination, the third light-emitting material in the region
excluding the region corresponding to the third pixel region is
adhered to the donor substrate and thus separated, and the third
light-emitting material in the region corresponding to the third
pixel region remains on the substrate, thereby forming a third
light-emitting material pattern.
18. The method according to claim 12, wherein the laser has a
transfer energy intensity of 5 to 40 kW/cm.sup.2.
19. The method according to claim 13, further comprising, after the
first light-emitting material pattern is formed, performing thermal
treatment to dry the substrate including the first light-emitting
material pattern.
20. The method according to claim 12, wherein the first pixel
region is a red pixel region, the second pixel region is a green
pixel region, and the third pixel region is a blue pixel region.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the benefit of Korean Patent
Application No. 10-2009-0116424, filed Nov. 30, 2009, in the Korean
Intellectual Property Office, the disclosure of which is hereby
incorporated by reference in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Aspects of the present invention relate to a laser induced
thermal imaging method, a method of patterning an organic layer
using the same, and a method of fabricating an organic light
emitting diode (OLED) display device using the same, and more
particularly, to a method of patterning an organic layer using a
reverse transfer phenomenon in a laser induced thermal imaging
method.
[0004] 2. Description of the Related Art
[0005] Today, the demand of a user to rapidly obtain exact
information in one's hand is growing due to the advent of the high
information age, and therefore, the development of display devices,
which are lightweight and slim which can be easily held, and have a
fast data processing speed, is rapidly progressing. Among the
display devices, an organic light emitting diode (OLED) display
device is a self-emitting device, which emits light by
recombination of an electron with a hole in an organic light
emitting layer when a voltage is applied to an organic layer
including the organic emitting layer. For this reason, the OLED
display device does not need a back light, unlike an LCD device,
and thus can be manufactured to have a lightweight and slim body
and have a simple process. In addition, the OLED display device has
the same level of response speed as a cathode ray tube (CRT), and
low voltage driving, high emission efficiency and a wide viewing
angle. For this reason, attention to the OLED display device is
increased sharply as a next generation display.
[0006] Here, according to the material for the organic layer,
particularly, the organic emitting layer, the OLED display devices
are classified into a small molecule OLED display device and a
polymer OLED display device.
[0007] The small molecule OLED display device includes multiple
organic layers having different functions, including a hole
injection layer, a hole transport layer, an emitting layer, a hole
blocking layer, and an electron injection layer, which are disposed
between an anode and a cathode. Here, the layers can be controlled
by being doped or replaced with a material having an appropriate
energy level to prevent accumulation of charges. However, since the
small molecule organic layer is formed by vacuum deposition, it is
difficult to be used to implement a large-sized display.
[0008] On the other hand, the polymer OLED display device may be
manufactured in a single-layer structure including an organic
emitting layer between an anode and a cathode, or in a double-layer
structure including a hole transport layer, so that the device
becomes thinner. The organic layer is formed by wet coating at
atmospheric pressure. As a result, a production cost can be
reduced, and a large-sized OLED display device can be easily
manufactured.
[0009] Here, a single-color device may be simply manufactured using
a polymer OLED display device by spin coating, but it has a lower
efficiency and a shorter lifespan than that manufactured using a
small molecule OLED display device. A full-color device may be
implemented by patterning emitting layers emitting the three
primary colors such as R, G, and B to the OLED display device.
Here, an organic layer of the small molecule OLED display device
may be patterned through deposition using a shadow mask, and an
organic layer of the polymer OLED display device may be patterned
through inkjet printing or laser induced thermal imaging (LITI).
Among them, the LITI method may utilize the characteristics of the
spin coating method, so that when it is applied to a large-sized
device, the device can obtain excellent uniformity in pixels. In
addition, since the LITI method is a dry process, not a wet
process, it can solve the problem of a decreasing lifespan due to a
solvent, and achieve a fine pattern of the organic layer.
[0010] To apply the LITI method, basically, a light source, and
organic light emitting diode substrates such as a substrate and a
donor substrate are needed. The donor substrate is composed of a
base layer, a light-to-heat conversion layer, and a transfer layer.
According to the LITI method, light emitted from the light source
is absorbed to the light-to-heat conversion layer of the donor
substrate, and converted into thermal energy. Thereby, an organic
material formed on the transfer layer is transferred to the
substrate.
[0011] FIGS. 1A and 1B are cross-sectional views illustrating a
conventional method of manufacturing an organic light emitting
diode display device through a LITI method.
[0012] Referring to FIG. 1A, an insulating substrate 101 is
prepared, and a first electrode 102 is formed on the insulating
substrate by patterning.
[0013] Subsequently, a pixel defining layer 103 defining R, G and B
pixel regions is formed, and thus a substrate 100 is completed.
[0014] Meanwhile, a light-to-heat conversion layer 32 and a
transfer layer 33 are sequentially stacked on a base layer 31, and
thus a donor substrate 30 is completed.
[0015] Afterwards, the pixel region of the substrate 100 is aligned
to face the transfer layer of the donor substrate 30, and laser is
irradiated to a region of the base layer 31 of the donor substrate
to be transferred.
[0016] Subsequently, referring to FIG. 1B, after an organic
light-emitting material is transferred to the pixel region of the
substrate 100, the donor substrate 30 is removed, thereby forming
an organic emitting layer pattern 33'.
[0017] Afterwards, as shown in FIG. 1C, a second electrode 104 is
formed on the organic layer, and thus an OLED display device can be
completed.
[0018] Consequently, according to the conventional art, to
manufacture an OLED display device through a LITI method, laser is
irradiated to the base layer in the region to be transferred to
transfer the organic light-emitting material to the pixel region of
the substrate.
[0019] However, due to the size (width) limit of a laser beam, the
size of a pattern which can be transferred by a cycle of a transfer
process is limited, and thus stitching mura occurs between widths
of the laser beams.
[0020] FIG. 2 is a photograph showing stitching mura occurring in
the conventional OLED display device manufactured by the LITI
method, and referring to FIG. 2, due to the size limit of the laser
beam, it can be seen that the stitching mura occurs between the
widths of the laser beams.
SUMMARY OF THE INVENTION
[0021] Aspects of the present invention provide a method of
patterning an organic layer which can prevent stitching mura
occurring between widths of laser beams due to the size limit of
the laser beam.
[0022] According to an aspect of the present invention, a laser
induced thermal imaging method includes: preparing a substrate
including a transfer layer; preparing a donor substrate including a
base layer and a light-to-heat conversion layer disposed on the
base layer; aligning the substrate with the donor substrate; and
irradiating laser to the base layer of the donor substrate. Here,
the laser is irradiated to the base layer in a region excluding a
region corresponding to a pattern to be formed on the
substrate.
[0023] According to another aspect of the present invention, a
method of patterning an organic layer includes: preparing a
substrate including an organic layer; preparing a donor substrate
including a base layer and a light-to-heat conversion layer
disposed on the base layer; aligning the substrate with the donor
substrate; and irradiating laser to the base layer of the donor
substrate. Here, the laser is irradiated to the base layer in a
region excluding a region corresponding to a pattern to be formed
on the substrate.
[0024] According to another aspect of the present invention, the
laser may have a transfer energy intensity of 5 to 40
kW/cm.sup.2.
[0025] According to another aspect of the present invention, after
the substrate is aligned with the donor substrate, the donor
substrate and the substrate may be laminated.
[0026] According to another aspect of the present invention, after
the laser is irradiated to the base layer of the donor substrate,
the donor substrate may be delaminated from the substrate.
[0027] According to another aspect of the present invention,
through the delamination, the organic layer in the region excluding
the region corresponding to the pattern to be formed on the
substrate may be adhered to the donor substrate and thus
separated.
[0028] According to still another aspect of the present invention,
a method of manufacturing an organic light emitting diode display
device includes: forming a first electrode layer on a substrate;
forming an insulating layer on the first electrode layer to define
a first pixel region, a second pixel region, and a third pixel
region; applying a first light-emitting material to the entire
surface of the substrate including the first, second and third
pixel regions; preparing a donor substrate including a base layer
and a light-to-heat conversion layer disposed on the base layer;
aligning the substrate with the donor substrate; and irradiating a
laser to the base layer of the donor substrate. Here, the laser is
irradiated to the base layer in a region excluding a region
corresponding to the first pixel region.
[0029] According to another aspect of the present invention, after
the laser is irradiated to the base layer in the region excluding
the region corresponding to the first pixel region, the donor
substrate may be delaminated from the substrate, and through the
delamination, the first light-emitting material in the region
excluding the region corresponding to the first pixel region may be
adhered to the donor substrate and thus separated, and the first
light-emitting material in the region corresponding to the first
pixel region may remain on the substrate, thereby forming a first
light-emitting material pattern.
[0030] According to another aspect of the present invention, the
method may further include applying a second light-emitting
material to the entire surface of the substrate including the first
light-emitting material pattern; preparing a donor substrate
including a base layer and a light-to-heat conversion layer
disposed on the base layer; aligning the substrate with the donor
substrate; and irradiating the laser to the base layer of the donor
substrate. Here, the laser may be irradiated to the base layer in a
region excluding a region corresponding to the second pixel
region.
[0031] According to another aspect of the present invention, after
the laser is irradiated to the base layer in the region excluding
the region corresponding to the second pixel region, the donor
substrate may be delaminated from the substrate, and, through the
delamination, the second light-emitting material in the region
excluding the region corresponding to the second pixel region may
be adhered to the donor substrate and thus separated, and the
second light-emitting material in the region corresponding to the
second pixel region may remain on the substrate, thereby forming a
second light-emitting material pattern.
[0032] According to another aspect of the present invention, the
method may further include applying a third light-emitting material
to the entire surface of the substrate including the first and
second light-emitting material patterns; preparing a donor
substrate including a base layer and a light-to-heat conversion
layer disposed on the base layer; aligning the substrate with the
donor substrate; and irradiating laser to the base layer of the
donor substrate. Here, the laser may be irradiated to the base
layer in a region excluding a region corresponding to a third pixel
region.
[0033] According to another aspect of the present invention, after
the laser is irradiated to the base layer in the region excluding
the region corresponding to the third pixel region, the donor
substrate may be delaminated from the substrate, and, through the
delamination, the third light-emitting material in the region
excluding the region corresponding to the third pixel region may be
adhered to the donor substrate and thus separated, and the third
light-emitting material in the region corresponding to the third
pixel region may remain on the substrate, thereby forming a third
light-emitting material pattern.
[0034] Additional aspects and/or advantages of the invention will
be set forth in part in the description which follows and, in part,
will be obvious from the description, or may be learned by practice
of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] These and/or other aspects and advantages of the invention
will become apparent and more readily appreciated from the
following description of the embodiments, taken in conjunction with
the accompanying drawings of which:
[0036] FIGS. 1A to 1C are cross-sectional views illustrating a
conventional process of manufacturing an organic light emitting
diode (OLED) display device by a laser induced thermal imaging
(LITI) method;
[0037] FIG. 2 is a photograph showing stitching mura occurring in
the conventional OLED display device manufactured by the LITI
method;
[0038] FIG. 3 is a cross-sectional view illustrating a transfer
mechanism of a common process of transferring an organic layer
according to a LITI method; and
[0039] FIGS. 4A through 4G are cross-sectional views illustrating a
process of manufacturing a full-color OLED display device using a
method of patterning an organic layer according to an embodiment of
the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0040] Reference will now be made in detail to the present
embodiments of the present invention, examples of which are
illustrated in the accompanying drawings, wherein like reference
numerals refer to the like elements throughout. The embodiments are
described below in order to explain the present invention by
referring to the figures.
[0041] Moreover, it is to be understood that where it is stated
herein that one film or layer is "disposed on" a second layer or
film, the first layer or film may be disposed directly on the
second layer or film or there may be intervening layers or films
between the first layer or film and the second layer or film.
Further, as used herein, the term "formed on" is used with the same
meaning as "located on" or "disposed on" and is not meant to be
limiting regarding any particular fabrication process.
[0042] FIG. 3 is a cross-sectional view illustrating a transfer
mechanism of a common process of transferring an organic layer
according to a LITI method. As shown in FIG. 3, according to a
common mechanism of transfer-patterning an organic layer using
laser, an organic layer S2 13 adhered to a substrate S1 is released
from the substrate S1 due to the action of laser, and transferred
to a substrate S3, resulting in separation from a portion
irradiated with laser.
[0043] A transfer characteristic is determined by a first adhesion
W12 between the substrate S1 and a film S2, a cohesion W22 between
films, and a second adhesion W23 between the film S2 and the
substrate S3.
[0044] The first and second adhesions are expressed by the
following equations, in which a surface tension of each layer is
represented as .gamma.1, .gamma.2, or .gamma.3, and an interfacial
tension of each layer is represented as .gamma.12 or .gamma.23.
W12=.gamma.1+.gamma.2-.gamma.12
W22=2.gamma.2
W23=.gamma.2+.gamma.3-.gamma.23
[0045] To improve the laser transfer characteristic, the cohesion
between the films should be smaller than the adhesion between each
substrate and the film.
[0046] Meanwhile, in order to transfer the transfer layer 13 from a
donor substrate 14 to a substrate 22 according to a general concept
of the transfer mechanism, laser is irradiated to a base layer 11,
and converted into thermal energy due to a light-to-heat conversion
layer 12 formed on the base layer 11, and an adhesion between the
transfer layer 13 and the light-to-heat conversion layer 12 is
changed. Thus, the transfer layer disposed in the region irradiated
with laser is transferred to the substrate.
[0047] However, the present inventors found that, when laser
transfer energy has a predetermined intensity or more, removing the
donor substrate 14 from the substrate 22 is performed fast, and the
transfer layer 13 disposed in the region irradiated with laser is
not transferred to the substrate 22, but remains on the donor
substrate 14, resulting in occurrence of a reverse transfer
phenomenon.
[0048] In other words, the reverse transfer phenomenon refers to a
phenomenon occurring when the adhesion W12 between the
light-to-heat conversion layer 12 and the transfer layer 13 is
larger than W23 between the substrate 22 and the transfer layer 13.
The present inventors found that the reverse transfer phenomenon
occurs when the laser transfer energy has a predetermined intensity
or more, and thus a novel method of patterning an organic layer
according to an aspect of the present invention was devised.
[0049] Hereinafter, a method of pattering an organic layer
according to an aspect of the present invention will be
described.
[0050] FIGS. 4A through 4G are cross-sectional views illustrating a
process of manufacturing a full-color OLED display device using a
method of patterning an organic layer according to an aspect of the
present invention.
[0051] While the method of manufacturing a full-color OLED display
device is illustrated for convenience of the description, there is
no limitation to an organic layer which can be manufactured by the
method of patterning an organic layer according to an aspect of the
present invention.
[0052] Referring to FIG. 4A, an insulating substrate 200 including
first, second and third pixel regions is provided, and a
transparent electrode material or a metal electrode material is
deposited and patterned on the substrate 200, thereby forming first
electrode layers 211R, 211G, and 211B in the first, second and
third pixel regions, respectively. The first electrode layers 211R,
211G, and 211B is formed of a reflective layer, that is, a metal
layer in a top emission structure, or formed of a transparent
electrode, ITO or IZO in a bottom emission structure. Here, a
second electrode layer 230 to be described later will be formed of
a transparent electrode in the top emission structure, or formed in
a structure in which a transparent electrode material is stacked on
a reflective layer formed of a metallic material, or a reflective
plate in the bottom emission structure. When the first electrode
layers 211R, 211G, and 211B are cathode electrode layers, the
second electrode layer 230 becomes an anode electrode layer, or
when the first electrodes 211R, 211G, and 211B are anode electrode
layers, the second electrode layer 230 becomes a cathode electrode
layer.
[0053] Afterwards, an insulating layer 210 is formed on the first
electrode layers 211R, 211G, and 211B to define red, green and blue
pixel regions R, G and B, respectively.
[0054] Here, the first pixel region may correspond to the red pixel
region, the second pixel region to the green pixel region, and the
third pixel region to the blue pixel region.
[0055] Then, referring to FIG. 4B, a red light-emitting material
220R, as a transfer layer, is applied to the entire surface of the
substrate including the insulating layer 210.
[0056] In other words, according to the conventional method of
manufacturing an OLED display device by a LITI method, a layer to
be transferred, that is, a transfer layer is formed on the donor
substrate, but according to an aspect of the present invention, the
transfer layer is formed on the substrate 200.
[0057] The red light-emitting material 220R may be dissolved in a
solvent and applied in a solution state by wet coating. The wet
coating methods may include spin coating, dip coating, spraying,
screen coating and inkjet printing. Other than them, a general
method used in the art can also be used.
[0058] Next, referring to FIG. 4C, the donor substrate 40 is
aligned with the top of the red light-emitting material 220R.
[0059] The donor substrate 40 includes a base layer 41 and a
light-to-heat conversion layer 42, which are sequentially
stacked.
[0060] Since laser is applied to the base layer, and transferred to
the light-to-heat conversion layer 42, the base layer 41 may be
formed of a transparent material. For example, the base layer 41
may be formed of at least one of the group consisting of polymer
materials such as polyester, polyacryl, polyepoxy, polyethylene,
and polystyrene, or a glass substrate. Preferably, but not
necessarily, the base layer 41 may be formed of
polyethyleneterephthalate.
[0061] The light-to-heat conversion layer 42 formed on the base
layer 41 is a layer absorbing light in a infrared-visible light
range, and converting a part of the light into heat, which may have
an appropriate optical density and include a light-absorbing
material for absorbing light. Here, the light-to-heat conversion
layer 42 may be formed of a metal layer composed of Al, Ag, and an
oxide and sulfide thereof, or an organic layer composed of carbon
black, graphite or a polymer containing an infrared dye. Here, the
metal layer may be formed by vacuum deposition, electron beam
deposition or sputtering, and the organic layer may be formed by a
conventional film coating method, for example, one of roll coating,
gravure, extrusion, spin coating, and knife coating.
[0062] Afterwards, the donor substrate 40 and the substrate 200 are
subjected to a lamination process. According to the lamination
process, the donor substrate 40 and the substrate 200 are fixed,
and compressed for lamination, thereby removing bubbles between the
donor substrate 40 and the substrate 200.
[0063] Then, laser is irradiated to the base layer 41 of the donor
substrate 40. Here, unlike the conventional art, laser is
irradiated to the base layer 41 in a region excluding a region
corresponding to a pattern to be formed on the substrate 200.
[0064] In other words, according to the conventional method of
manufacturing an OLED display device by a LITI method, laser is
irradiated to the base layer in a region to be transferred, and an
organic light-emitting material is transferred to the pixel region
of the substrate.
[0065] However, in an aspect of the present invention, after a
material for a layer to be transferred is formed on the entire
surface of the substrate 200, the donor substrate 40 and the
substrate 200 are aligned and subjected to lamination.
Subsequently, laser is irradiated to the base layer 41 of the donor
substrate 40, excluding the region corresponding to the pattern to
be formed on the substrate 200. Thus, in this operation, since a
material for a layer to be transferred is a red light-emitting
material 220R, laser is irradiated to the base layer 41 in the
region excluding the region corresponding to the red pixel region
211R.
[0066] In other words, since an organic layer is patterned using
the reverse transfer phenomenon described above, the irradiated
laser is converted into thermal energy due to the light-to-heat
conversion layer formed on the base layer, and the adhesion between
the layer of the red light-emitting material 220R and the
light-to-heat conversion layer 42 is created by the thermal energy,
and becomes larger than the adhesion between the substrate 200 and
the red light-emitting material 220R.
[0067] Here, for the reverse transfer phenomenon, the laser
transfer energy should have a predetermined intensity or higher
than a predetermined intensity, which may be 5 kW/cm.sup.2 or
more.
[0068] Even if the laser transfer energy has an intensity of less
than 5 kW/cm.sup.2, the reverse transfer phenomenon may occur.
However, for effective transfer quality, the laser transfer energy
may have an intensity of 5 kW/cm.sup.2 or more.
[0069] Meanwhile, the laser transfer energy may have an intensity
of 40 kW/cm.sup.2 or less. If the laser transfer energy has an
intensity of more than 40 kW/cm.sup.2, the organic layer may be
damaged.
[0070] Subsequently, referring to FIG. 4D, a red light-emitting
material pattern 220R' is formed on the substrate 200 through
delamination which is used to separate the donor substrate 40 from
the substrate 200.
[0071] In other words, when the delamination process is performed
to separate the donor substrate 40 from the substrate 200, the
region excluding the region corresponding to a pattern to be formed
on the substrate has an adhesion between the light-heat conversion
layers due to the irradiation of laser, thereby being adhered to
the donor substrate and thus separated. The region corresponding to
the pattern to be formed on the substrate is not irradiated with
laser, so that it cannot see any change in adhesion, and the region
remains on the substrate 200.
[0072] Subsequently, referring to FIG. 4E, a green light-emitting
material 220G is applied to the entire surface of the substrate 200
including the red light-emitting material pattern 220R'.
[0073] The green light-emitting material 220G is dissolved in a
solvent and applied in a solution state by wet coating. The wet
coating methods may include spin coating, dip coating, spraying,
screen printing and inkjet printing, and other than them, a general
method in the art can also be used.
[0074] Afterwards, the donor substrate 40 is aligned with the top
of the green light-emitting material 220G, and the donor substrate
40 and the substrate 200 are subjected to lamination. Subsequently,
laser is irradiated to the base layer of the donor substrate 40.
Here, the laser is irradiated to the layer of the green
light-emitting material 220G by the same method as irradiating
laser to the red light-emitting material 220R. That is, the laser
is irradiated to the base layer in the region excluding the region
corresponding to the pattern to be formed on the substrate 200.
Meanwhile, in this operation, since a material for the layer to be
transferred is a green light-emitting material, laser is irradiated
to the base layer 41 in a region excluding a region corresponding
to the green pixel region 211G.
[0075] Subsequently, referring to FIG. 4F, a green light-emitting
material pattern 220G' is formed on the substrate 200 through
delamination which is used to separate the donor substrate 40 from
the substrate 200.
[0076] Here, the green light-emitting material pattern 220G' is
formed by the same principle as forming the red light-emitting
material pattern 220R', and thus a detailed description thereof
will be omitted.
[0077] Meanwhile, when the green light-emitting material 220G is
formed on the entire surface of the substrate to form the green
light-emitting material pattern 220G', the substrate also includes
the red light-emitting material pattern 220R', and thus the green
light-emitting material 220G is formed on the red light-emitting
material pattern 220R'.
[0078] In this case, in the delamination process which separates
the donor substrate 40 from the substrate 200 to form the green
light-emitting material pattern 220G', can also be used to remove
the red light-emitting material pattern 220R'.
[0079] For this reason, after the red light-emitting material
pattern 220R' is formed, heat treatment may be performed to dry the
substrate including the red light-emitting material pattern
220R'.
[0080] To be specific, after the red light-emitting material
pattern 220R' is formed, the transferred material is treated with
heat to solidify and fix, thereby changing an interfacial
characteristic of the red light-emitting material pattern 220R',
and thus declining an adhesion strength between the red
light-emitting material pattern 220R' and the layer of the green
light-emitting material 220G. As a result, the layer of the green
light-emitting material 220G may be easily separated from the red
light-emitting material pattern 220R' through the delamination
process performed to separate the donor substrate 40 from the
substrate 200.
[0081] Such process can be a concern when different organic layers
are patterned on the substrate, however, this is not the case when
a single material layer is formed on the substrate by patterning
the organic layer according to an aspect of the present
invention.
[0082] Subsequently, referring to FIG. 4G, like the method of
forming the green light-emitting material pattern 220G', a blue
light-emitting material is applied to the entire surface of the
substrate 200 including the red and green light-emitting material
patterns 220R' and 220G', and a blue light-emitting material
pattern 220B' may be formed by the patterning method as described
above. Thus, a detailed description thereof will be omitted.
[0083] Afterwards, a second electrode layer 230 is formed on the
entire surface of the substrate 200 including the red, green and
blue light-emitting material patterns 220R', 220G' and 220B', and
subjected to a conventional encapsulation process, thereby
manufacturing a full-color OLED display device according to an
exemplary embodiment of the present invention.
[0084] Here, the organic layer of the full-color OLED display
device according to an embodiment of the present invention may
further include a hole injection layer, a hole transport layer, a
hole blocking layer, an electron transport layer, and an electron
injection layer between the first electrode layer 211 and the
second electrode layer 230 by the method of patterning an organic
layer.
[0085] In other words, as described above, as the transfer layer
formed on the substrate 200, materials for emitting layers such as
red, green and blue light-emitting materials are described, but the
transfer layer may also be formed of a single layer selected from
the group consisting of organic layers such as an emitting layer, a
hole injection layer, a hole transport layer, an electron injection
layer, and an electron transport layer, or a multiple layer
including at least two thereof.
[0086] Since, in an aspect of the present invention, the organic
layer is patterned using a reverse transfer phenomenon, laser is
irradiated to the base layer in the region excluding the region
corresponding to the pattern to be formed on the substrate.
[0087] To be specific, according to the conventional art, laser is
irradiated to the region corresponding to the pattern to be formed
on the substrate, so that when the pattern to be formed is larger
than the size (width) of the laser beam, transfer is impossible and
therefore must be accomplished by a cycle of transfer processes.
Accordingly, several cycles of the transfer processes are needed to
form a pattern, and thus stitching mura occurs between the widths
of the laser beams. However, according to an aspect of the present
invention, laser is irradiated to the region excluding the region
corresponding to the pattern to be formed on the substrate,
regardless of the size of the pattern to be formed and the size
(width) of the laser beam, thereby preventing stitching mura.
[0088] Consequently, according to an aspect of the present
invention, since laser is irradiated to a region excluding a region
corresponding to a pattern to be formed on a substrate, stitching
mura can be prevented regardless of the size of the pattern to be
formed and the size (width) of the laser beam.
[0089] Although a few embodiments of the present invention have
been shown and described, it would be appreciated by those skilled
in the art that changes may be made in this embodiment without
departing from the principles and spirit of the invention, the
scope of which is defined in the claims and their equivalents.
* * * * *